Journal of Supramolecular Chemistry最新文献

Single crystals of two calix[4]arene derivatives, that is, 5,11,17,23-tetra-tert-butyl- 25,27-bis[2-[N-(3-methoxy-4-methoxy-benzylidene)-amino]ethoxy]-26,28- dihydroxy calix[4]arene (1) and 5,11,17,23-tetra-tert-butyl-25,27-bis[2-[3- pyridine carbonyl-amino]ethoxy]-26,28-dihydroxy calix[4]arene (2), were prepared and their crystal structures have been determined by X-ray crystallographic study. As compared with calix[4]arene derivative 1 possessing CN functional group, compound 2 bearing the NH group could form not only intermolecular hydrogen bonds between the hydrogen atom in NH group and the oxygen atom in CO of an adjacent calix[4]arene molecule, but also intramolecular hydrogen bonds between the N—H⋯OC moieties in solid state, giving a rare linear molecular aggregation.

Mixing FeBr₃ either solid or dissolved in ethyl ether, in acetonitrile or in dichloromethane with solid β-cyclodextrin, form different type of FeBr₃-cyclodextrin complexes as indicated by their stoichiometric composition and thermal and spectroscopic properties. The complexes are stable under usual atmospheric conditions. Water solutions of FeBr₃ at pH 12 containing cyclodextrin are stable over 24 h. The solid complexes were characterized by DSC and TGA analysis as well as by IR spectroscopy. It is shown that the complexes obtained from the reaction of solid cyclodextrin with FeBr₃ dissolved in ethyl ether, acetonitrile, or dichloromethane catalyze the oxidation of methyl phenyl sulfide to methyl phenyl sulfoxide although in different yields. The best complex for this purpose is the one prepared in CH₂Cl₂ which afforded the sulfoxide in good yield.

Mono-Schiff bases containing crown ether ring (HL¹, HL², HL³ and HL⁴) and their transition-metal complexes were synthesized and characterized by ¹H NMR, IR, MS spectra and elemental analysis. The crystal structures of HL¹, HL³ and CoL₂¹ were determined from X-ray diffraction data. The oxygenation constants (Ko₂) of Schiff-base Co (II) complexes were measured over a range of −5 °C to 25 °C, and the values of ΔH⁰ and ΔS⁰ were also calculated based on Ko₂. In the presence of Mn (III) Schiff base complexes, the biomimetic catalytic oxidation for styrene to benzalhyde was carried out at 100% selectivity. Compared with the uncrowned analogue, the influence of crown ring and its bonding pattern, the distance between the coordination center and crown ring on the dioxygen affinities and biomimetic catalytic oxidation performance of the crowned Schiff base complexes were observed.

Two chromatographic stationary phases, obtained by covalently linking two suitably derivatized calix[4]crown-6 and calix[4]crown-5 receptors onto silica gel, are described here. A study of their chromatographic behaviour as well as their surface composition is reported. The packing materials exhibit high selectivity toward alkali metal ions. Complete separations of Cs⁺ from K⁺ and Na⁺ were obtained when using a water/methanol mixture (80:20) as the mobile phase. In these conditions, a selectivity factor Cs⁺/Na⁺=4.10 was achieved with the silica gel-bound calix[4]crown-6. The degree of coverage of the activated silica-gel surface following the covalent attachment of the macrocycle was estimated by mean of X-ray photoelectron spectroscopy (XPS). This technique allows the first few monolayers of the material to be analysed and thus is to be preferred to conventional Elemental Analysis for similar studies. Three methods for an adequate correction of the XP signals for the presence of organic contaminants are suggested and critically compared.